ES2729058T3 - Preparation process of a polyunsaturated ketone compound - Google Patents

Abstract

A process for preparing a polyunsaturated ketone comprising: (1) reacting a polyunsaturated alcohol in the presence of a compound of formula R2-SO2Hal in which R2 is a C1-20 hydrocarbyl group, such as a C1-10 alkyl group, to form a polyunsaturated sulfonyl ester; (2) convert the polyunsaturated sulfonyl ester into a polyunsaturated thioester by reacting with an anion of the formula - SC (= O) R4 in which R4 is a C1-20 hydrocarbyl group; (3) convert the polyunsaturated thioester to optionally form a polyunsaturated thiol in the presence of an antioxidant, for example using a metal carbonate; (4) reacting said polyunsaturated thiol with a compound (LG) R3COX in which X is an electron extraction group, R3 is an alkylene group and LG is a leaving group; optionally in the presence of an antioxidant, to form a polyunsaturated ketone compound.

Description

DESCRIPTION

Preparation process of a polyunsaturated ketone compound.

Field of the Invention

This invention relates to a method of manufacturing a polyunsaturated thiol compound and the subsequent conversion of that thiol compound into a polyunsaturated ketone. In particular, the invention relates to the conversion of a polyunsaturated alcohol into a polyunsaturated thiol compound that allows the conversion of that polyunsaturated thiol into a polyunsaturated ketone. The invention avoids unwanted oxidation reactions and cis / trans isomeric reactions are substantially reduced or eliminated during synthesis. We also achieved a very high overall performance.

Background

Many biologically active polyunsaturated fatty acids have one or more carbon-carbon double bonds in the cis configuration. It has been reported that free radicals support the isomerization of these bonds to a less desirable trans configuration. Cis / trans isomerization can adversely affect polyunsaturated compounds intended for pharmaceutical use, for example, by reducing biological activity and / or complicating synthesis. See, for example, C. Ferreri et al. (2007) Mol. Biotech 37:19; Chatgilialoglu, C et al. (2002) Free Rrad. Biology & Medicine, 33: 1681; and WO 2002/100991.

It has been reported that some, but not all, free radicals support cis / trans isomerism of particular polyunsaturated compounds. It is believed that the kinetics of radical-mediated oxidation depend on several parameters, including the chemical nature of the unsaturated compound, temperature, pH, the presence or absence of light, oxygen, etc. It has been reported that free radicals occur naturally in the environment or as unwanted byproducts that are produced from certain chemical reactions. See, for example, Mengele, E.A et al. (2010) Mos. Univ. Chemistry Bull 65: 210.

Attempts have been made to reduce the oxidation and cis / trans isomerism of the carbon-carbon double bonds. In one approach, an antioxidant such as octyl gallate, ascorbic acid, polyphenol, mercaptoethanol, beta-carotene, or 2,6, -ditert-butyl-4-methylphenol (BHT), for example, is added to reduce unwanted oxidation reactions. See Mengele, EA, ibid; Klein, E and N. Weber (2001) J. Agric. Food Chem. 49: 1224; and Hung, WL, et al. (2011) J. Agric. Food Chem. 1968.

It is reported that certain polyurethyl ketone polyunsaturated compounds have useful biological activities. See, for example, U.S. Patent No. 7,687,543; Huwiler, A et al. (2012) Br. J. Pharm. 167: 1691.

Methods of preparing particular polyunsaturated ketones have been described. In a method describing the synthesis of particular polyunsaturated trifluoromethyl ketones, a Mitsunobu type reaction was used to transform an alcohol into the corresponding thioester. Other chemical reactions were said to produce polyunsaturated trifluoromethyl ketone (compound 18 therein) with a yield of 71%. See Holmeide, A and L. Skattebol (2000) J. Chem. Soc. Perkin Trans. 1: 2271. However, there is concern that this procedure may lead to double racemization and unwanted oxidation reactions.

There is a general recognition that a compound intended for pharmaceutical use must be produced in high yield, for example, 70% or more. Less than satisfactory yields can be associated with unwanted by-products. These can be expensive or difficult to remove from the main product (API), which makes pharmaceutical development even more difficult. Additionally, regulatory agencies often require a detailed analysis of secondary products in compounds intended for pharmaceutical use. This requirement can make expansion costs prohibitive.

The present inventors seek a process for the manufacture of a polyunsaturated thiol and, finally, a corresponding polyunsaturated ketone that produces, after appropriate purification, a pharmaceutical grade compound with minimal oxidation and cis / trans isomerization by products. After extensive synthetic work, the inventors have determined that a particular process as claimed herein offers an ideal route for the compounds of the invention, since the process operates with minimal oxidation and cis / trans isomerization by products. The procedure described in this document not only reaches a very high purity, but also a very high yield. It can also be easily extended to industrial operation.

Summary of the Invention

The present inventors have found that the oxidation or racemization of double bonds is a serious problem for the molecules described herein. The chemistry described in this document avoids or at least reduces the formation of racemized products and allows the formation of a polyunsaturated thiol that can be used in Additional (known) synthesis steps to form desired target molecules. More specifically, a method of manufacturing a polyunsaturated thiol compound has been found, which can finally be converted into the advantageous ketone compounds discussed herein, in which undesired oxidation reactions and cis / trans isomerization are substantially reduce or eliminate. The methods of practice of the invention can be used to produce a variety of polyunsaturated ketone compounds suitable for pharmaceutical use, including those specified herein.

Therefore, an object of the invention is to prepare pharmaceutically acceptable polyunsaturated thiol compounds, which can finally be converted into the advantageous ketone compounds described herein, in which the undesired oxidation and cis / trans isomerization reactions are substantially reduce or eliminate. The method of invention involves the conversion of an alcohol into a sulfonyl ester polyunsaturated (ie, a compound comprising the group -OSO ² -Rx wherein Rx is a hydrocarbyl group C ^{1 to 20),} conversion of the sulfonyl ester a thioester (formula - Scory where Ry is a hydrocarbyl group C ^{1 to 20)} and then reducing this thioester to a thiol (-SH) in the presence of an antioxidant.

It is also an object of the invention to provide the target compounds in high purity, such as that often required by regulatory authorities.

Preferably, the subsequent steps towards the formation of the polyunsaturated ketone are also performed in the presence of a pharmaceutically acceptable antioxidant to minimize the potential for cis / trans oxidation or isomerization in subsequent reactions.

It is also within the scope of the invention if the polyunsaturated alcohol used is prepared through the contact of a polyunsaturated aldehyde with an appropriate electrophilic reducing agent under conditions sufficient to make the polyunsaturated alcohol. It is once again believed that the use of mild electrophilic reducing agents reduces the unwanted reduction of double bonds, which helps the overall synthesis to achieve better purity.

Thus, seen from one aspect, the invention provides a process for preparing a polyunsaturated thiol comprising:

(1) reacting a polyunsaturated alcohol in the presence of a compound of formula R ² -SO ² Hal where R ² is a hydrocarbyl group C ^1-20, alkyl group said C ¹ - ^10, to form a polyunsaturated sulfonyl ester;

(2) converting the sulfonyl ester polyunsaturated a polyunsaturated thioester to react with the anion of formula -SC (= O) R4 wherein ^R4 is a hydrocarbyl group C ^{1 to 20;}

(3) convert the polyunsaturated thioester into a polyunsaturated thiol optionally in the presence of an antioxidant. Seen from another aspect, the invention provides a process for preparing a polyunsaturated ketone compound comprising:

stages (1) to (3) above and subsequently,

(4) reacting said polyunsaturated thiol with a compound (LG) R3COX in which X is an electron extraction group and R3 is an alkylene group carrying a leaving group (LG), such as the formation of LG-CH ²

that is, where R3 is -CH ² - where X is an electron extraction group and LG is a leaving group; optionally in the presence of an antioxidant, to form a polyunsaturated ketone compound, ideally of formula (VIII) as defined herein.

Seen from another aspect, the present disclosure provides the product of a procedure as defined above.

Seen from another aspect, the invention provides a process for preparing a polyunsaturated thiol of formula (VII) or (VII ')

R-SH or R'-SH (VII) or (VII ')

which includes:

(1) react a polyunsaturated alcohol of formula

R-OH or R'-OH (I) or (I ')

wherein R is an optionally substituted C ^9-23 unsaturated hydrocarbon group optionally interrupted by one or more heteroatoms or groups of heteroatoms selected from S, O, N, SO, SO ² , said hydrocarbon group comprising at least 2, preferably at least 4 double bonds; Y

wherein R 'is an unsubstituted, linear C ^9-23 unsaturated hydrocarbon group, said hydrocarbon group comprising at least 2, preferably at least 4 double bonds;

in the presence of a compound of formula R ² -SO ² Hal where R ² is a hydrocarbyl group C ^{1 to 20,} such as an alkyl group C ¹ - ^10, to form a compound of formula sulfonyl ester of polyunsaturated (V) or (V ')

R-BEAR ² R ² or PINK ² R ² (V) or (V ')

(2) convert the polyunsaturated sulfonyl ester (V) or (V ') into a polyunsaturated thioester by reacting with an anion of the formula -SC (= O) R4 in which R ⁴ is a C ^1-20 hydrocarbyl group to form a polyunsaturated thioester compound of formula (VI) or (VI '):

R-SCOR ⁴ or R'-SCOR4 (VI) or (VI ')

in which R and R 'are as defined above in this document;

(3) convert the polyunsaturated thioester optionally in the presence of an antioxidant and optionally in the presence of a metal carbonate to form a polyunsaturated thiol compound of formula (VII) or (VII ')

R-SH or R'-SH (VII) or (VII ').

in which R and R 'are as defined above in this document.

Seen from another aspect, the invention provides a method that includes at least the following steps: (1) react (3Z, 6Z, 9Z, 12Z, 15Z) -octadeca-3,6,9,12,15-pentaen-1 -ol

or (2E, 6Z, 9Z, 12Z, 15Z,) - octadeca-2,6,9,12,15-pentaen-1-ol;

with methanesulfonyl chloride in the presence of a base to form a

or

( ² ) react the reaction product of step ( ¹ ) with a thioacetate ion to form a thioester of the formula:

(3) react the product of step (2) with potassium carbonate in the presence of an antioxidant to form a thiol of formula: or

(4) optionally, contacting the thiol produced in step (3) with 3-bromo-1,1,1-trifluoroacetone under conditions that produce

where X is CF ³ .

In any process of the invention, it is further preferred that the polyunsaturated alcohol be obtained by reduction of its corresponding aldehyde in the presence of an electrophilic reducing agent such as DIBAH (diisobutylaluminium hydride).

Viewed from another aspect, the present disclosure provides a pharmaceutical composition comprising the product of a process as defined hereinbefore and at least one pharmaceutically acceptable excipient.

Definitions

The term polyunsaturated in the term polyunsaturated thiol or polyunsaturated thioester and so on refers to compounds containing a hydrocarbon chain containing multiple double bonds, that is, ² or more.

That chain is preferably free of any ring. It is preferred that the double bonds present are not conjugated.

The term Hal means halide, that is, F, Cl, Br or I, preferably Cl or Br.

The term C ^1-20 hydrocarbyl group refers to a group containing 1 to 20 carbon atoms and only H atoms. The group may be a C ^1-10 hydrocarbyl group, such as a C ^1-10 alkyl group, C ^2-10 alkenyl, C ^6-10 aryl group, alkylaryl C ^7-10, C ^7-10 arylalkyl group, C ^3-10 cycloalkyl group, C ^4-10 alkylcycloalkyl or cycloalkylalkyl C ^4-10 and so on. As long as there are only C and H atoms present and up to 20 carbon atoms, any arrangement of those atoms is possible. Any hydrocarbyl group is preferably a C ^1-10 alkyl group. Any hydrocarbyl group is preferably a linear C ^1-10 alkyl group.

In general, any polyunsaturated compound of the invention will have an Mw of less than 500 g / mol, preferably 450 g / mol or less, more preferably 400 g / mol or less.

The term "pharmaceutically acceptable" means that it is useful in the preparation of a pharmaceutical product that is generally non-toxic and is not biologically undesirable and includes that which is acceptable for veterinary use and / or for pharmaceutical use in humans.

Detailed description of the invention

This invention relates to a process for the manufacture of a polyunsaturated thiol and, ultimately, a polyunsaturated ketone. The procedure offers high yields and high purity. In particular, it is envisioned that, after proper purification, the steps of the process of the invention provide the target compounds in pharmaceutical quality. The procedure can also be easily extended for industrial operation.

The invention provides a way of making a polyunsaturated thiol and the subsequent conversion of that thiol into a ketone under conditions that provide the compounds in yields and purities that are often required by regulatory authorities. For example, and without wishing to limit itself to any theory, it is believed that the production of unwanted oxidation products and the unwanted double bond racemization can be decreased or even eliminated by following the techniques described herein.

The starting material in the process of the invention is a polyunsaturated alcohol. Preferably that polyunsaturated alcohol is of formula (I)

R-OH (I)

wherein R is an optionally substituted C ^9-23 unsaturated hydrocarbon group, optionally interrupted by one or more heteroatoms or groups of heteroatoms selected from S, O, N, SO, SO ² , said hydrocarbon group comprising at least 2, preferably at minus 4 double links.

It is preferred if in any R group, double bonds are not conjugated. The group R preferably comprises 5 to 9 double bonds, preferably 5 or 8 double bonds, for example, 5 to 7 double bonds, such as 5 or 6 double bonds.

It is also preferred if the double bonds do not conjugate with the hydroxyl group.

The double bonds present in the R group may be in the cis or trans configuration, however, it is preferred that most of the double bonds present (that is, at least 50%) be in the cis configuration. In further advantageous embodiments, all double bonds in group R are in the cis configuration or all double bonds are in the cis configuration, except for the double bond closest to the OH group that may be in the trans configuration.

The R group may have between 9 and 23 carbon atoms, preferably 11 to 19 carbon atoms, especially 16 to 18 carbon atoms. The carbon atoms are preferably linear in the R group. While the R group may be interrupted by at least one heteroatom or group of heteroatoms, this is not preferred and the main chain of the R group preferably contains only carbon atoms.

The R group may be optionally substituted, for example, may carry up to three substituents, for example, selected from halo, C ^1-6 alkyl, for example, methyl, C ^1-6 alkoxy. If present, the substituents are preferably non-polar and small, for example, a methyl group. However, it is preferred, if the R group remains unsubstituted.

The group R is preferably linear, that is, there are no branches in the R chain. It is preferably derived from a natural source such as a fatty acid or long chain ester. In particular, the R group can be derived from arachidonic acid, docosahexaenoic acid or eicosapentaenoic acid.

Thus, it is preferred if the polyunsaturated alcohol is a compound of formula (I ')

R'-OH (I)

wherein R 'is a linear unsubstituted C ^9-23 unsaturated hydrocarbon group, said hydrocarbon group comprising at least 2, preferably at least 4 double bonds. Ideally, R 'is an alkenylene group having 9-23 carbon atoms and at least 2, such as at least 4 double bonds. Preferred options for R also apply to the definition of R '.

It may be that the polyunsaturated alcohol used in the invention is derived from a corresponding fatty acid or aldehyde. Furthermore, it has been found that when the polyunsaturated alcohol is derived from its corresponding aldehyde, that polyunsaturated alcohol is preferably obtained in a reaction that involves contacting a polyunsaturated aldehyde with an appropriate electrophilic reducing agent under conditions sufficient to make the polyunsaturated alcohol. Without wishing to be bound by any theory, it is believed that the use of mild electrophilic reducing agents reduces the unwanted reduction of double bonds, which helps the overall synthesis achieve better yields and purity. The polyunsaturated aldehyde is, therefore, preferably of the formula R-CHO or R'CHO where R and R 'are as defined hereinbefore.

The use of diisobutylaluminum hydride (DIBAH) is particularly preferred in this regard. The present inventors have surprisingly found that some other well known reducing agents such as sodium borohydride cannot be used successfully in this reduction since they increase the number of impurities formed. It is surprising that the use of DIBAH seems to reduce isomerism and, therefore, minimize the formation of impurities.

The invention further comprises therefore the conversion of a compound of formula (II) or (II ')

R ¹ CHO or R ¹ CHO (II) or (II ')

for R-OH or R'-OH using DIBAH where R and R 'are as defined hereinbefore and R ¹ and Rr are equivalent to R and R' from which a terminal bond -CH ² - is removed. It will be appreciated that the definition of R ¹ and Rr depends on the definition of R and R '. During the reduction of the aldehyde a group -CH ² is generated - which is part of the definition of R or R 'and, therefore, the chains R ¹ and Rr are a shorter carbon than those or R and R'. Viewed alternatively, the reaction involves reduction:

R ¹ CHO or R ¹ CHO (II) or (II ') ^ R ¹ CH ² -OH or for RVCH ² -OH (III) or (III')

wherein R1 is an optionally substituted C ^8-22 unsaturated hydrocarbon group, optionally interrupted by one or more heteroatoms or groups of heteroatoms selected from S, O, N, SO, SO ² , said hydrocarbon group comprising at least 2, preferably at minus 4 double bonds; and wherein R ¹ 'is an unsubstituted, linear unsubstituted C ^8-22 hydrocarbon group, said hydrocarbon group comprising at least 2, preferably at least 4 double bonds. Preferred options for R also apply to the definition of R ¹ and Rr (subtracting a carbon atom from any carbon limit).

The aldehyde can be prepared by any appropriate technique such as those described in J Chem Soc Perkin Trans 1, 2000, 2271-6. Alternatively, a protocol can be followed as described in Molecules 2014 (19), 3804-3811. An appropriate procedure would be:

In another embodiment as explained in J Chem Soc Perkin Trans 1, 2000, 2271-6, the alcohol can be prepared through a reduction of a fatty acid ester, conversion into an epoxide, reduction thereof to an aldehyde, isomerization optional and additional reduction. The following scheme summarizes the reactions for AVX001:

The alcohol for the production of AVX002 can be prepared directly from an aldehyde reduction without isomerization.

It is preferred that the alcohol starting material used in the process of the invention be purified using normal phase column chromatography or, preferably, reverse phase column chromatography.

Therefore, in one embodiment, the alcohol starting material for the process of the invention is obtained through the following reactions:

R2SO2Hal (IV)

wherein R ² is a C ^1-20 hydrocarbyl group, preferably a C ^1-10 hydrocarbyl group, especially a C ^1-10 alkyl group, such as a C ^1-4 alkyl group, especially methyl. R ² is preferably a linear C ^1-20 hydrocarbyl group such as a linear C ^1-10 alkyl group.

The halide (hal) can be F, Cl, Br or I, especially Br or Cl, more especially Cl.

The reaction of the polyunsaturated alcohol with the sulfonyl halide is preferably carried out in the presence of a base, ideally to neutralize any halide acid (for example, HCl) that is formed during the reaction. The base must not react with polyunsaturated compounds. Appropriate bases are well known in the art, such as trialkylamines, in particular triethylamine. Therefore, well-known non-nucleophilic bases are appropriate. This reaction preferably forms, therefore, a compound of formula (V) or (V '):

R-BEAR ² R ² or PINK ² R ² (V) or (V ')

in which R, R 'and R ² are as defined above in this document.

For the avoidance of doubt, R-OSO ² R ² has the structure:

Step (2) of the process of the invention requires the conversion of the sulfonyl ester (V) / (V ') into a thioester. The group -OSO ² R ² thus becomes the group -SC (= O) R4.

This can be achieved by reaction using a compound comprising a salt with an -SCOR ⁴ ion where R ⁴ is a C ^1-20 hydrocarbyl group. The counterion can be a metal such as an alkali metal, for example Li, Na or K. R ⁴ is preferably a C ^1-10 hydrocarbyl group, especially a C ^1-10 alkyl group, such as a C ^1-6 alkyl group , especially a C ^1-4 alkyl group such as methyl. Any group R ⁴ is preferably linear. Thus, the use of thioacetate ions is preferred.

The reaction forms a compound (VI) or (VI ')

R-SCOR ⁴ or R'-SCOR4 (VI) or (VI ')

where R, R 'and R ⁴ are as defined earlier in this document.

In step (3) of the process, this thioester is then converted to a thiol. While this may, in theory, be carried out using any conventional procedure, for example, using diisobutylaluminum hydride, to avoid side reactions, impurity formation and cis-trans isomerization of the double bonds present, the inventors propose to carry out this reaction in the presence of an antioxidant.

It is preferred if the antioxidant is a small molecule such as one having a molecular weight of 500 g / mol or less, such as 250 g / mol or less. The antioxidant should ideally be approved for use by the FDA. The antioxidant used is preferably butyl hydroxyanisole, butyl hydroxytoluene, propyl gallate, tocopherol, ascorbic acid, ascorbyl palmitate, thioglycerol, thioglycolic acid, sodium bisulfite, sodium sulfite, sodium metabisulfite, tetrasodium edetate, EDTA.

The use of tocopherol is especially preferred, particularly (+/-) - alpha-tocopherol.

The amount of antioxidant added / present may be of the order of 0.01 to 1 mol%, preferably 0.1 to 0.5 mol% with respect to the amount of polyunsaturated thioester present (in moles).

Also, the above beneficial effects can be further enhanced by making the polyunsaturated thiol in a reaction that involves contacting a polyunsaturated thioester with an appropriate mild electrophilic reducing agent under conditions sufficient to make the polyunsaturated thiol. Without wishing to be bound by any theory, it is believed that the use of mild electrophilic reducing agents, as explained below, reduces the unwanted reduction of double bonds, which helps the overall synthesis achieve better yields and purity.

Suitable reducing agents are ideally metal carbonates such as alkali metal carbonates, especially potassium carbonate. The use of a solvent such as methanol is appropriate. Therefore, the use of a metal carbonate together with an antioxidant is especially preferred.

Preferred thiols that are formed are simply of formula (VII) or (VII ')

R-SH or R'-SH (VII) or (VII ')

where R and R 'are as defined earlier in this document.

Ideally, the thiol should have a purity of at least 90% as determined by HPLC (% area) at this point. More preferably, the purity should be 91% or more, such as 92% or more, ideally 93% or more, especially 94% or even 95% or more.

It has been found that the process herein produces thiol in high yield, for example, 70% or more of step (1), such as 75% or more, even 80% or more. Also, the presence of detectable impurities in HPLC can be eliminated.

Ideally, of course, the process of the invention is directed to a variety of pharmaceutically acceptable polyunsaturated ketones that are suitable for pharmaceutical use. Preferred compounds include a ketone group comprising an electron extraction group and a sulfur atom at position a, p, and or 8 of the ketone group. An electron extraction group or EWG extracts electrons from a reaction center.

The preferred polyunsaturated ketone targets of the invention are therefore of formula (VIII)

R5-CO-X (VIII)

wherein R5 is a C ^10-24 polyunsaturated hydrocarbon group interrupted at position a, p, and 8 of the ketone group by an S atom; Y

X is an electron extraction group (EWG).

The appropriate electron extraction groups X for any compound of the invention are CN, phenyl, CHal3, CHabH, CHalH ² , in which Hal represents a halogen, especially F. The EWG is especially CHab, for example. CF ³ .

It is more preferred if the S atom is beta to carbonyl (thus forming an RS-CH ² COCF ^{3 group} where R is as defined hereinbefore).

It is preferred if in any R5 group, double bonds are not conjugated. The R5 group preferably comprises 5 to 9 double bonds, preferably 5 or 8 double bonds, for example, 5 to 7 double bonds, such as 5 or 6 double bonds.

It is also preferred if the double bonds do not conjugate with the carboxyl group.

The double bonds present in the R5 group may be in the cis or trans configuration, however, it is preferred that most of the double bonds present (that is, at least 50%) be in the cis configuration. In further advantageous embodiments, all double bonds in group R5 are in the cis configuration or all double bonds are in the cis configuration, except for the double bond closest to group S which may be in the trans configuration.

The R5 group may have between 10 and 24 carbon atoms, preferably 12 to 20 carbon atoms, especially 17 to 19 carbon atoms. The R5 group is thus preferably an alkenylene group having between 10 and 24 carbon atoms, preferably 12 to 20 carbon atoms, especially 17 to 19 carbon atoms and at least two double bonds. The R5 group is preferably linear.

Therefore, ideally, the target compounds of the invention are of the formula R-SCH ² COCF ³ or R'SCH2COCF3 where R and R 'are as defined hereinbefore.

In a preferred embodiment, the invention provides a production method of 1,1,1-trifluoro-3 - (((2E, 6Z, 9Z, 12Z, 15Z,) - octadeca-2,6,9,12,15 Pharmaceutically acceptable pentaein-1-yl) uncle) propan-2-one:

where X is CF ³ ; or related compound

where X is CF3.

The last stage of the process of the invention therefore involves the reaction of thiol with an appropriate ketone to form the desired compounds of formula (VIII). The reaction preferably implies that a compound is of formula (LG) R3 ^c OX where R3 reflects the atoms necessary to complete the group R5 where R5 = RS-R3-; this is

F$H

F $ H

(LG} RaCOX

T

r 5GO *

R3 is preferably C ^1-3 alkylene, such as methylene. LG represents a leaving group that is nucleophilically substituted with the thiol group. A leaving group is a molecular fragment that separates with a pair of electrons in the cleavage of the heterolytic bond. Of course, preferably, (LG) R3-COX represents the compound LG-CH ² -COX, where LG is a leaving group such as a halide, tosyl, mesyl, and so on. Ideally, LG is a halide such as Br. X is an electron extraction group as defined hereinbefore in the above formulas, preferably CF ³ again. More preferably (LG) R3-COX is BrCH2-COCF3.

This final reaction step can take place in the presence of an antioxidant as defined hereinbefore. An antioxidant may inherently be present as a result of the thioester conversion stage and, in that scenario, it may not be necessary to add more antioxidant. It is within the scope of the invention, however, to add more antioxidant, for example where the thiol formed was purified and, therefore, antioxidants were removed.

It is preferred if the antioxidant is a small molecule such as one having a molecular weight of 500 g / mol or less, such as 250 g / mol or less. The antioxidant should ideally be approved for use by the FDA. The antioxidant used is preferably butylhydroxyanisole, butyl hydroxytoluene, propyl gallate, tocopherol, ascorbic acid, ascorbyl palmitate, thioglycerol, thioglycolic acid, sodium bisulfite, sodium sulfite, sodium metabisulfite, tetrasodium edetate, EDTA.

The use of tocopherol is especially preferred, particularly (+/-) - alpha-tocopherol.

The reaction of thiol to ketone can also be favored by the use of a mild base such as a hydrogen carbonate salt to favor the nucleophilic attack of thiol in the leaving group of the ketone reagent. It will be appreciated that the reaction products of each step of the process of the invention can be purified using well known procedures.

It will be appreciated that the compounds of the invention are primarily for medicinal use and, therefore, any antioxidant preferably used is pharmaceutically acceptable.

The amount of antioxidant added to the polyunsaturated thiol may be between 0.01 and 1 mol%, 0.1 to 0.5 mol% of the polyunsaturated thiol.

It has also been learned that the presence of a pharmaceutically acceptable antioxidant can be used in the present methods to help reduce unwanted cis / trans isomerization without being destroyed or otherwise blocked.

It will be appreciated that any reaction described herein may be necessary in the absence of oxygen, for example under an Ar atmosphere.

Ideally, the ketone formed by the process of the invention should have a purity of at least 90% as determined by HPLC (% area) at this point. More preferably, the purity should be 91% or more, such as 92% or more, ideally 93% or more, especially 94% or even 95% or more.

It has been found that the process in this document produces the ketone with high yield, for example 70% or more of step (1). Also, the presence of detectable impurities in HPLC can be eliminated.

In a more preferred embodiment, the process of the invention includes at least the following steps:

(1) react (3Z, 6Z, 9Z, 12Z, 15Z) -octadeca-3,6,9,12,15-pentaen-1-ol

or (2E, 6Z, 9Z, 12Z, 15Z) - octadeca-2,6,9,12,15-pentaen-1-ol;

with methanesulfonyl chloride in the presence of a base to form a

(2) react the reaction product of step (1) with a thioacetate ion to form a thioester of the formula:

(3) react the product of step (2) with potassium carbonate in the presence of an antioxidant to form a thiol of formula:

or

(4) optionally contacting the thiol produced in step (3) with 3-bromo-1,1,1-trifluoroacetone under conditions that produce

where X is CF ³ .

In particular, the invention relates to the procedure summarized in scheme 1:

That compound can be purified by dry column vacuum chromatography (Synthesis, 2001; 16: 2431-2434) to a purity of at least 90% as determined by HPLC (% area) to produce a pharmaceutically acceptable compound.

The invention also relates, in particular, to the procedure summarized in method 1:

Method 1

The compound of the invention can also be purified, for example by normal phase or reverse phase chromatography to produce a pharmaceutically acceptable compound.

It will be appreciated that the compounds made in the process of the invention have a variety of applications, for example, in the treatment of chronic inflammatory disorders. They can be formulated as pharmaceutical compositions using well known techniques. They can be converted into salts when appropriate. An additional discussion of such techniques is not required in this document.

The invention will now be described with reference to the following non-limiting examples.

Example 1

AVX002 Preparation

methanesulfonyl chloride (1.7 mL, 22.0 mmol) with stirring, followed by triethylamine (5.5 mL, 39.4 mmol). A precipitation formed immediately, giving a grout. The cooling bath was removed and the reaction mixture was stirred for one hour. The reaction mixture was poured into water (200 mL), 40 mL of 1M HCl was added and the aqueous phase was extracted with diethyl ether (3 x 50 mL). The combined organic phase was washed with 5% NaHCO3 (aq., 50 mL) and brine (50 mL) and subsequently dried over Na2SO4. Filtration and evaporation of the solvent under reduced pressure produced 6.40 g (95.9% yield) of 2 in the form of an orange-yellow oil, which was used in the next step without purification. 1H NMR (CDCls, 300 MHz): d 0.97 (3H, t, J = 7.5 Hz), 2.07 (2H, dq, J1 = J2 = 7.3 Hz), 2.54 (2H, dt, J1 = J2 = 6.9 Hz), 2.78-2.88 (8H, m), 3.00 (3H, s), 4.22 (2H, t, J = 6.9 Hz), 5.25-5.46 (9H, m), 5.51-5.62 (1H, m). MS (ES): m / z 361 (M + Na) +.

To a solution of 2 (6.40 g, 18.9 mmol) in dry DMF (65 mL) was added potassium thioacetate (8.48 g, 74.2 mmol) in one portion, accompanied by a slight color change to brown and an increase in viscosity The reaction mixture was stirred in an inert atmosphere for 1.5 hours at room temperature and poured into water (500 mL). The product was extracted with ether (3 x 100 mL) and the combined organic phases were washed with brine (2 x 100 mL) and dried over Na2SO4. After filtration, the solvent was removed under reduced pressure, giving 5.76 g of crude product. Subsequent purification using dry column vacuum chromatography (DCVC, elution gradient n-heptane-100: 1 n-heptane: ethyl acetate) gave 5.60 g of 3 (93.0% yield) as a pale yellow oil. 1H NMR (CDCls, 400 MHz): d 0.97 (3H, t, J = 7.5 Hz), 2.08 (2H, dq, J1 = J ² = 7.1 Hz), 2.32 (3H, s), 2.35 (2H, dt, J1 = J ² = 7.0 Hz), 2.79-2.87 (8H, m), 2.90 (2H, t, J = 7.3 Hz), 5.27-5.49 (10H, m). MS (ES): m / z 341 (M +

Compound 3 (5.60 g, 17.6 mmol) was dissolved in methanol (50 mL) containing 10 mg of a-tocopherol. Potassium carbonate (2.68 g, 19.4 mmol) was added in one portion at room temperature and the mixture was stirred for 45 minutes under an inert atmosphere. The reaction mixture was quenched by the dropwise addition of 50 mL of 1M HCl, while cooling the mixture in an ice bath. The mixture was subsequently extracted with heptane (3 x 50 mL) and the combined organic phases were washed with brine (50 mL) and dried over Na2SO4. After filtration and removal of the solvent under reduced pressure, 4.77 g of 4 (98.0% yield) were obtained as a pale yellow oil.

Spectral data, compound 4

1H NMR (CDCla, 400 MHz): 0.98 (3H, t, J = 7.5 Hz), 1.43 (1H, t, J = 7.7 Hz), 2.08 (2H, dq, J1 = J ² = 7.5 Hz), 2.40 ( 2H, dt, J1 = J ² = 7.0 Hz), 2.57 (2H, dt, J1 = J ² = 7.3 Hz), 2.79-2.89 (8H, m), 5.29-5.43 (9H, m), 5.46-5.53 ( 1H, m).

The crude product was used in the next step without further purification.

Sodium hydrogen carbonate (1.97 g, 23.4 mmol) was added to thiol 4 (3.07 g, 11.1 mmol), followed by water (40 mL) and ethanol (60 mL). The resulting inhomogeneous mixture was vigorously stirred at room temperature for 20 minutes in an inert atmosphere. Then 3-bromo-1,1,1-trifluoroacetone (1.40 mL, 13.3 mmol) was added in one portion, and stirring was continued for 45 minutes. The reaction mixture was extracted with n-heptane (2 x 50 mL). The combined organic phase was washed with brine (50 mL), dried over Na2SÜ4, filtered and concentrated under reduced pressure. The crude product was purified using dry column vacuum chromatography (DCVC, gradient elution n-heptane-100: 10 n-heptane: ethyl acetate). The pure fractions were combined, and subsequent evaporation of the solvent under reduced pressure gave 3.43 g of 5 (79.9% yield) as a colorless oil.

Spectral data, compound 5:

1 H NMR (hydrated / non-hydrated mixture), CDCb, 400 MHz): 0.98 (3H, t, J = 7.5 Hz), 2.08 (2H, dq, J = J2 = 7.2 Hz), 2.39 (2H, m), 2.57 (1H, t, J = 7.3 Hz), 2.77 (1H, t, J = 7.5 Hz), 2.80-2.88 (8H, m), 2.92 (1H, s), 3.51 (1H, s), 3.98 (1H , s), 5.29-5.51 (10H, m). 13C NMR (hydrated / non-hydrated mixture, CDCla, 100 MHz): 14.2, 20.5, 25.5, 25.58, 25.60, 25.67, 25.70, 26.5, 27.1, 31.7, 33.3, 34.7, 36.4, 92.4 ( q, J ^cf = 31 Hz), 115.5 ( q, J ^cf = 293 Hz), 122.9 ( q, J ^cf = 286 Hz), 126.8, 127.0, 127.1, 127.7, 127.77, 127.79, 127.9, 128.0, 128.3, 128.40, 128.43, 128.55,128.57 , 130.1, 130.2, 131.99, 132.01, 185.0 ( q, J ^cf = 34 Hz). MS (ES): m / z 385 (MH ⁺ ) ^f

Example 2

AVX001 Preparation

To a solution of ¹ (5.03 g, 19.3 mmol) in dry tetrahydrofuran (50 mL) at 0 ° C was added methanesulfonyl chloride (1.7 mL, 22.0 mmol) with stirring, followed by triethylamine (5.5 mL, 39.4 mmol). A precipitation formed immediately, giving a grout. The cooling bath was removed and the reaction mixture was stirred for one hour. The reaction mixture was poured into water (200 mL), 40 mL of 1M HCl was added and the aqueous phase was extracted with diethyl ether (3 x 50 mL). The combined organic phase was washed with 5% NaHCÜ3 (aq., 50 mL) and brine (50 mL) and subsequently dried over Na2SÜ4. Filtration and evaporation of the solvent gave a quantitative yield of 2 crude, which was used directly in the next step without purification.

The crude product of 2 was dissolved in dry DMF (65 mL), to which potassium thioacetate (8.83 g, 77.3 mmol) was added in one portion, accompanied by a color change to brown and a large increase in viscosity . The reaction mixture was stirred in an inert atmosphere overnight at room temperature and quenched with water (500 mL). The product was extracted with ether (3 x 100 mL) and the combined organic phases were washed with brine (2 x 100 mL) and dried over Na2SÜ4. After filtration, the solvent was removed under reduced pressure, giving 5.44 g of raw product. Subsequent purification using dry column vacuum chromatography (DCVC, gradient elution n-heptane - 100: 1 n-heptane: ethyl acetate) gave 5.27 g of 3 (85.5% yield in two stages) as a colored oil orange. 1 H NMR (CDCb, 400 MHz): 0.98 (3H, t, J = 7.5 Hz), 2.04-2.16 (6H, m), 2.33 (3H, s), 2.79 2.85 (6H, m), 3.49 (2H, 2 , J = 7.2 Hz), 5.29-5.48 (9H, m), 5.62-5.69 (1H, m). MS (ES): m / z 341 (M + Na) +.

Compound 3 (5.27 g, 16.5 mmol) was dissolved in methanol (50 mL) containing 10 mg of a-tocopherol. Potassium carbonate (2.53 g, 18 mmol) was added in one portion at room temperature and the mixture was stirred for 45 minutes under an inert atmosphere. The reaction mixture was quenched by the dropwise addition of 50 mL of 1M HCl, while cooling in an ice bath. Subsequently, the mixture was extracted with heptane (3 x 50 mL) and the combined organic phases were washed with brine (50 mL). Drying over Na2SO4 and subsequent filtration and removal of the solvent under reduced pressure provided 4.45 g of 4 (97.5% yield) as an orange oil. The crude product was used in the next step without further purification.

Sodium hydrogen carbonate (2.87 g, 34.2 mmol) was added to thiol 4 (4.45 g, 16.1 mmol), followed by water (50 mL) and ethanol (75 mL). The resulting inhomogeneous mixture was vigorously stirred at room temperature for 20 minutes in an inert atmosphere. Then 3-bromo-1,1,1-trifluoroacetone (2.1 ml, 20 mmol) was added in one portion, and stirring was continued for 45 minutes. The reaction mixture was extracted with n-heptane (2 x 100 ml). The combined organic phase was washed with brine (50 mL), dried over Na2SO4, filtered and concentrated under reduced pressure. This produced 6.26 g of raw product.

From the crude product, two aliquots of 2.00 g were extracted and further purified using two different methods.

An aliquot was applied to a 90 g column of silica and eluted by dry column vacuum chromatography (DCVC, 100 mL fractions, gradient elution n-heptane-100: 2 n-heptane: ethyl acetate). The pure fractions were combined and evaporation of the solvent under reduced pressure gave 1.64 g of 5 as a pale yellow oil. This corresponds to a yield of 82.5% for the last stage.

A second aliquot was applied to a column with 90 g of stationary phase ODS-AQ. Elution was performed by means of DCVC (100 mL fractions, gradient elution 20:80 acetonitrile: water - 70:30 acetonitrile: water), and after evaporation of acetonitrile from the fractions containing the pure product, the product it was extracted again to an organic solvent with 3 x 100 mL of n-heptane. The combined organic extracts were washed with brine (50 mL), dried over Na2SO4, filtered and concentrated under reduced pressure to give 1.28 g of 5 as a pale orange oil. This corresponds to a yield of 64.4% for the last stage.

The mass and NMR spectral data are similar, except for the hydrated / non-hydrated ratio in NMR. The data given are for the purification method B).

1 H NMR (hydrated / non-hydrated mixture), CDCb, 400 MHz): 0.98 (3H, t, J = 7.5 Hz), 2.08 (2H, dq, J1 = J ² = 7.4 Hz), 2.12-2-21 ( 4H, m), 2.76-2.89 (6H, m), 3.10 (0.5H, t, J = 7.5 Hz), 3.26 (1.5H, t, J = 7.5 Hz), 3.45 (0.5H, s), 3.93 ( 1.5H, s), 5.28-5.46 (9H, m), 5.56-5.66 (1H, m). MS (ES): m / z 385 (M-H +) '.

Claims (15)

1. A process for preparing a polyunsaturated ketone comprising: (1) reacting a polyunsaturated alcohol in the presence of a compound of formula R ² -SO ² Hal where R ² is a hydrocarbyl group C ^{1 to 20,} such as an alkyl group C ¹ - ^10, to form a sulfonyl ester polyunsaturated; (2) converting the sulfonyl ester polyunsaturated a polyunsaturated thioester to react with the anion of formula -SC (= O) R4 wherein ^R4 is a hydrocarbyl group C ^{1 to 20;} (3) convert the polyunsaturated thioester to optionally form a polyunsaturated thiol in the presence of an antioxidant, for example using a metal carbonate; (4) reacting said polyunsaturated thiol with a compound (LG) R3COX in which X is an electron extraction group, R3 is an alkylene group and LG is a leaving group; optionally in the presence of an antioxidant, to form a polyunsaturated ketone compound. 2. A method according to claim 1, comprising: (1) react a polyunsaturated alcohol of formula (I) or (I ') R-OH or R'-OH (I) or (I ') wherein R is an optionally substituted C ^9-23 unsaturated hydrocarbon group optionally interrupted by one or more heteroatoms or groups of heteroatoms selected from S, O, N, SO, SO ² , said hydrocarbon group comprising at least 2, preferably at least 4 double bonds; Y wherein R 'is a linear unsubstituted unsubstituted C ^9-23 hydrocarbon group, said hydrocarbon group comprising at least 2, preferably at least 4 double bonds; in the presence of a compound of formula R ² -SO ² Hal where R ² is a hydrocarbyl group C ^1-20, alkyl group such C ¹ - ^10, to form a sulfonyl ester compound polyunsaturated formula (V) or ( V ') R-BEAR ² R ² or PINK ² R ² (V) or (V ') (2) convert the polyunsaturated sulfonyl ester (V) or (V ') into a polyunsaturated thioester by reacting with an anion of the formula -SC (= O) R4 in which R ⁴ is a C ^1-20 hydrocarbyl group to form a polyunsaturated thioester compound of formula (VI) or (VI '): R-SCOR ⁴ or R'-SCOR4 (VI) or (VI ') in which R and R 'are as defined above in this document; (3) convert the polyunsaturated thioester optionally in the presence of an antioxidant and optionally in the presence of a metal carbonate to form a polyunsaturated thiol compound of formula (VII) or (VII ') R-SH or R'-SH (VII) or (VII '). in which R and R 'are as defined above in this document. 3. A method according to claim 2, comprising at least the following steps: (1) react (3Z, 6Z, 9Z, 12Z, 15Z) -octadeca-3,6,9,12,15-pentaen-1-ol

or (2E, 6Z, 9Z, 12Z, 15Z) - octadeca-2,6,9,12,15-pentaen-1-ol;

with methanesulfonyl chloride in the presence of a base to form a

(2) react the reaction product of step (1) with a thioacetate ion to form a thioester of the formula:

(3) react the product of step (2) with potassium carbonate in the presence of an antioxidant to form a thiol of formula:

(4) contacting the thiol produced in step (3) with 3-bromo-1,1,1-trifluoroacetone under conditions that produce

where X is CF ³ . 4. A method according to any preceding claim, wherein R is a C ^11-19 linear unsubstituted carbon chain comprising at least 4 unconjugated double bonds. 5. A process as claimed in any preceding claim, wherein the R-OH or R'-OH polyunsaturated alcohol is obtained by reduction of its corresponding aldehyde R ¹ CHO or R ¹ CHO in the presence of an electrophilic reducing agent such as DIBAH (diisobutylaluminum hydride) in which R ¹ or Rr are as defined for R and R ', respectively, in which a -CH ² -terminal bond (eg, a C ^10-18 carbon chain is not removed) Linear substituted comprising at least 4 double conjugated links). 6. A process according to any of the preceding claims, wherein the sulfonyl halide is a C ^1-4 alkylsulfonyl chloride such as methanesulfonyl chloride. 7. A process according to any preceding claim, wherein the reaction with the sulfonyl halide takes place in the presence of a base, such as an amine. 8. A process according to any preceding claim, wherein R ⁴ is a C ^1-4 alkyl such as methyl to form a thioacetate anion, preferably potassium thioacetate. 9. A process according to any of the preceding claims, wherein the formation of thiol takes place in the presence of a metal carbonate, preferably potassium carbonate. 10. A process according to any preceding claim wherein an antioxidant is present in step (3) and the antioxidant is hydroxyanisole butyl, hydroxytoluene butyl, propyl gallate, tocopherol, ascorbic acid, ascorbyl palmitate, thioglycerol, thioglycolic acid, bisulfite sodium, sodium sulphite, sodium metabisulfite, tetrasodium edetate or EDTA. 11. A method according to claim 10, wherein the antioxidant is tocopherol, for example, a-tocopherol. 12. A method according to any preceding claim wherein the product is purified using normal or reverse phase column chromatography. 13. A method according to any preceding claim wherein the polyunsaturated alcohol is purified using normal or reverse phase column chromatography. 14. A method according to claim 1, comprising: or

15. A process according to claim 1, wherein R3 is methylene such that (LG) R3COX is: